Diagnosis

Legionnaires' disease is similar to other types of pneumonia. To help identify the presence of legionella bacteria quickly, your doctor may use a test that checks your urine for legionella antigens — foreign substances that trigger an immune system response. You may also have one or more of the following:

Blood tests

Chest X-ray, which doesn't confirm legionnaires' disease but can show the extent of infection in your lungs

Tests on a sample of your sputum or lung tissue

A CT scan of your brain or a spinal tap (lumbar puncture) if you have neurological symptoms such as confusion or trouble concentrating

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